Can't fit top front differential bushing inserts (KDT925)

[Ohio Enthusiast]

I installed Whiteline differential bushings (KDT925) just now, and couldn't get the top front bushings installed. The instructions say to support the front of the diff, remove the bolts and lower the diff. When I did it the diff barely lowered by half an inch, and even prying it with a crowbar didn't have significant movement. After that I loosened (but not removed) the rear bolts as well, but the diff still didn't budge.

I ended up installing all the bushings in the kit except those front top ones. Bolted everything back, torqued to spec and did a test drive. Everything is great, and the little driveline lash I had remaining after the rear subframe bushings and transmission inserts is now gone, with only minor added NVH.

Did anyone else experience an issue with these bushings? I was hesitant to completely remove the diff bolts (2 front and 3 rear), not knowing at which point I need to support the diff with the bottle jack.

[DarkPira7e]

I'd recommend unbolting the driveshaft and the rear bolts when doing this

[Ohio Enthusiast]

At which point should I support the diff? Or it doesn't matter much with the prop shafts still connected?

[euniqe]

Personally I made the mistake of leaving the car in gear when attempting to lower the diff. I pushed the clutch in, and voila, it lowered instantly.

You should be supporting the diff at all times with a jack or stand or whatever, and only lower it slightly to allow room to insert the bushing inserts. The axles and prop shaft aren't designed to hold the weight of it.

[Ohio Enthusiast]

Originally Posted by euniqe

Personally I made the mistake of leaving the car in gear when attempting to lower the diff. I pushed the clutch in, and voila, it lowered instantly.

Hmm, I'm pretty sure I moved to neutral after jacking the car up, but I may have forgotten. I had the same issue with installing the rear transmission bushing, with the same experience (pushed the clutch in, transmission lowered and bushing went in without a hitch, after fighting it for half an hour). Next time I'm under the car I'll give it a go. Thanks!

[Plumbus]

Originally Posted by Ohio Enthusiast

Hmm, I'm pretty sure I moved to neutral after jacking the car up, but I may have forgotten. I had the same issue with installing the rear transmission bushing, with the same experience (pushed the clutch in, transmission lowered and bushing went in without a hitch, after fighting it for half an hour). Next time I'm under the car I'll give it a go. Thanks!

Let us know how it goes, I'm doing this mod in the near future as well.

[skylinekin]

You can always remove the 2 rear bolts in addition to the front bolts and support the whole diff with a jack and lower the whole thing down for more clearance.

[Ohio Enthusiast]

Originally Posted by Plumbus

Let us know how it goes, I'm doing this mod in the near future as well.

Next time I have a chance under the car would probably be in a month or so to switch to winter tires. I'll be sure to report back.

[Ohio Enthusiast]

@Plumbus - reporting back - I probably had the transmission in gear in my first try. Now I made sure to pop it in neutral before unbolting the 2 front support bolts and lowering the diff on the bottle jack. It wasn't loose enough to compress the bottle jack, but a little levering with the jack's handle dropped the diff a couple of inches without a problem.

[solidONE]

Lube and stretch. Make it fit.

[solidONE]

Originally Posted by Ohio Enthusiast

@Plumbus - reporting back - I probably had the transmission in gear in my first try. Now I made sure to pop it in neutral before unbolting the 2 front support bolts and lowering the diff on the bottle jack. It wasn't loose enough to compress the bottle jack, but a little levering with the jack's handle dropped the diff a couple of inches without a problem.

I thought you couldnt press the top bushing over the carrier.. I think the urathane shrinks a tad so the inner diameter of the thin bushing will be slightly smaller than the portion of the carrier its supposed to fit over.

If that's where you are at now.. lube and stretch. make it fit.

[Ohio Enthusiast]

Originally Posted by solidONE

I thought you couldnt press the top bushing over the carrier.. I think the urathane shrinks a tad so the inner diameter of the thin bushing will be slightly smaller than the portion of the carrier its supposed to fit over.

Yeah, it's not a perfect fit - the inserts basically just sits on top, without the snug fit of other bushing inserts for the car (especially compared to the rear subframe inserts). It does snug up well when tightening (as per Whiteline's instructions on a crush fit).

BTW, I only had a chance today to test drive the BRZ after putting these bushing in and it made a noticeable difference vs. the rest of the diff inserts. I'm very happy with this kit.

[solidONE]

Originally Posted by Ohio Enthusiast

Yeah, it's not a perfect fit - the inserts basically just sits on top, without the snug fit of other bushing inserts for the car (especially compared to the rear subframe inserts). It does snug up well went tightening (as per Whiteline's instructions on a crush fit).

BTW, I only had a chance today to test drive the BRZ after putting these bushing in and it made a noticeable difference vs. the rest of the diff inserts. I'm very happy with this kit.

Its a very worthy mod.. even on a brand spanking new 86, me thinks.